1. Field of the Invention
The present invention relates to a recording head which is configured such that a plurality of head modules are connected in one direction, a method for producing the recording head, and a recording device having the recording head.
2. Description of the Related Art
An ink jet printer (recording device) is known, in which ink is ejected from a plurality of nozzles provided in an ink jet head (recording head) so as to form an image on a recording medium. As a recording method of the ink jet printer, a line type printer is known in which an image is recorded by transport of a recording medium and a single drawing pass performed by the ink jet head. In the line type printer, as the ink jet head, a long line head is used, which is configured such that a plurality of head modules having nozzles two-dimensionally arranged are connected in a width direction (main scanning direction) of the recording medium.
In this ink jet printer, concentration unevenness may occur on a recording image due to variation in ejection characteristics (for example, variation in an ejection amount of ink or a landing position of ink) of each nozzle of the ink jet head. Accordingly, in the ink jet printer, in general, in order to solve the concentration unevenness, the occurrence of the concentration unevenness is suppressed by correcting image data based on a concentration unevenness correction table or by correcting image data based on a gradation correction table for each predetermined unit. However, when the ink jet head is the line head, an ejection amount (droplet amount) of ink in a connection portion between head modules adjacent to each other is not continuous. In addition, when a difference of ejection amounts in the connection portion is large, it is not possible to completely correct the concentration unevenness.
JP2007-22092A discloses an ink jet printer in which when characteristics of concentration changes of images recorded by an ink jet head are shown by line graphs, image data in which the line graphs draw lines having gradients is generated, and image recording is performed based on the image data. According to the ink jet printer of JP2007-22092A, since a level difference of concentration in the connection portion of the head modules is suppressed, the occurrence of the concentration unevenness is relatively prevented.
JP2007-160834A discloses an ink jet printer, in which head modules are disposed in order of average ejection amounts or average ejection amounts of a first head module and an Nth head module are made to be the same as each other such that differences of the average ejection amounts between the first head module and the Nth head module are approximately constant. According to the ink jet printer of JP2007-160834A, since the lines of the head modules are regulated such that the level differences of the average ejection amounts decrease, the level differences of concentrations in the connection portion of the head modules are relatively suppressed, and as a result, the occurrence of the concentration unevenness is prevented.